It should take a few in-game days.

But, if you want my advice, don't waste your time with Arabians. They may look good on paper, but they are extremely cowardly.

You're better off with a Missouri Fox Trotter but if you're early in, maybe an Ardennes or a Dutch Warmblood

Meh don’t let em talk you down, calm button

How much is arabian if you sell them? is it worth it?

@Babangeo

Its not really worth it. Selling a fully bonded white Arabian at the horse fence will only get you about $360.